Absorbent articles are known and commonly used in personal care absorbent products such as diapers, training pants, sanitary napkins, incontinence garments, bandages and the like. The invention also relates to a process for making said article.
Nowadays, the absorbing element in the article is comprised of high absorbency materials such as superabsorbents (Super Absorbent Polymers—SAP—), which form the diaper's absorbent core.
While the SAP has many advantages, it is also difficult to dose, given the fact that SAP is available as a powder. The problem is not acute for uniform layers dispensing devices, but becomes very relevant when SAP patterns are required.
EP-A-1621166 discloses a process for producing absorbent core structures, comprising the steps of:                providing a carrier material;        providing a support for said carrier material, the support having a support pattern;        providing a carrier material holding means (especially vacuum applying means);        positioning said carrier over said support means, whereby said carrier contacts said support;        providing a pre-metered amount of SAP particulate material;        providing a cover material for sandwiching with the carrier;        
and wherein                said carrier material is supported only in the region of the support pattern of the support means;        said carrier material is deformed by said carrier holding means such that indentations are formed in the unsupported regions:        said SAP particulate material being transferred to said carrier material into said indentations thereby forming a primary pattern of particulate material.        
EP-A-1621167, a companion application of the above EP-A-1621166, discloses a process for producing absorbent core structures, comprising substantially the same steps, and wherein the process comprises the steps of:                providing a SAP particulate material;        providing a transfer device for receiving said SAP particulate material in a receiving region and transferring it to an discharging region;        said transfer device comprising a first pattern forming means.        
In the above processes, the pattern is formed by the indentations formed in the unsupported regions. This provides for a poor uniformity, and the depth of the clusters formed by the indentations is rather limited. Also, the entire pattern is formed during one operation. The dispensing of the SAP particulate material makes use of a feeding hopper, this being derived from the helio-cylindrical printing system. The volume of the delivered SAP cannot be changed, while the SAP particulate material can vary because of different suppliers. Any change requires a change in the engraving of the dispensing roll. Further, high speeds are not possible with such systems. Last, in order to have a dosing that is reliable, it is necessary to compact the SAP in the discharging regions, which does not facilitate the complete release into the clusters and provides for attrition and shearing forces applied by the hopper to the SAP, which is a fragile material and subject then to degradation.
The above techniques thus still do not completely solve the problems of the distribution of SAP in cavities formed in the absorbent article.
Consequently, there is a need for an improved process for forming liquid-absorbing article containing SAP where the SAP is distributed according to a given pattern, and where the SAP is delivered in a fast and reliable manner.